Coated paper



Patented Feb. 25, 1941 UNITED STATES PATENT OFFICE COATED PAPER tion of Indiana No Drawing.

Original application December 16, 1936, Serial No. 116,233.

Divided and this application September 25, 1940, SerialNo. 358,311

6 Claims.

This invention relates to the method of coating paper and packaging materials with hydrocarbon products such as paraflin wax, petrolatum, and refined oils.

When paramn wax, petrolatum, refined oils, or white oils are used to coat or impregnate paper and packaging materials it has been found that these hydrocarbon products deteriorate rapidly and form undesirable odors resembling a rancid 10' odor. Consequently, the utility of the paper as a forming rancid odors.

means for wrapping food products is greatly impaired. Even. though antioxidants may have been added to the oil or wax prior to its impregnation in the paper, it has been found that the thus treated paper still has the tendency to de-. velop rancid odors in relatively short periods of time.

One of the objects of my invention is to prepare a. paper or packaging material, of the cellulosic type, coated with paraffin wax, petrolatum, or refined mineral oils which may be used to wrap food products such as bread, butter, lard and the like. Papers prepared in accordance with my process may be stored for long periods of time without Consequently the food products or materials encased with the coated paper will not become contaminated with undesirable odors which result from the deterioration of the oil or wax in the paper.

I have discovered that paper is a pro-oxidant for paraffin waxes and refined. mineral oils and that when such oils or waxes are used to coat or impregnate paper, their stability is quickly impaired. For example, a parafiin wax, petrolatum,

' or refined mineral oil which can be stored at room temperature for as long as several years before becoming rancid, will become rancid in as little as two or three months when stored as waxed, petrolatum-impregnated, or oiled paper. Furthermore, when paraflin waxes and refined oils containing a small percent of antioxidants are used to impregnate paper, it has been found that the wax or oil developed rancid odor in a much shorter time than the same wax or oil before its impregnation in the paper.

I have discovered that by impregnating or covering the surface of paper with an antioxidant prior to theapplication oi paraifinwax, petrolatum,.refined wax, or a refined oil that the catalytic' efiect of the paper upon the coating will be greatly retarded. In carrying out my invention, the paper is impregnated with an antioxidant before adding the paraflln wax or oil coating. This operation'may be performed in many ways, for example, the paper is passed through an aqueous solution of the antioxidant and then permitted to dry. The thus treated paper is then passed through a bath of molten paraffin wax or refined oil in order to apply the coating. By this means, the interface between the paper and wax or paper and oil contains an antioxidant which destroys the pro-oxidant effect of the paper upon the hydrocarbon material. a

The antioxidants may be applied to the paper in any suitable manner, ,for example, when the paper is made in the conventional type of process a water bath containing the antioxidant may be placed between the paper presses and the drying rolls. If desired, a solution of the antioxidant may be sprayed onto the paper at any point in its process of manufacture providing precautions are taken to prevent substantial amounts of the antioxidants from being washed out of the finished product. The antioxidant may also be applied to the paper in the vapor phase; the paper being passed through a chamber containing steam and the vapor oi the antioxidant to be used, e. g. beta-naphthol. In drying paper that has been impregnated with the antioxidant, precaution should be taken not to overheat the paper during the drying operation. Excessive heating during the drying operation may partly destroy the efiectiveness of the antioxidant.

, In the event that the particular antioxidant to be used is not suificiently soluble in water to prepare concentrated solutions, the paper may be soaked in a saturated aqueous solution or suspension of the antioxidant. Also volatile solvents may be used for the antioxidants, namely, ether,-

alcohol and the like, or emulsified solutions of the antioxidant. In preparing a paper impregnated with catechol, I have found that by soaking the paper in a 0.1% aqueous solution of catechol for about 15 minutes, a suflicient amount of the antioxidant will defuse into the paper to destroy the pro-oxidant efiect of the paper upon the hydrocarbon coating to be applied. Solutions containing various amounts of the antioxidants, .ior example 1% to 0.001%, may be employed in orderto impregnate the paper. and particularly the surface of the paper with the desired antioxidant. Also, solutions containing an admixture of the hereinafter mentioned antioxidants may also be employed.

The paraflin waxes having various melting points may be used to impregnate p p rs and Package materials in accordance with my inven-' tion. Waxes having melting points from 122-124, 130-132 and 135-138 F., are examples of waxes that may be used. Refined oils, for example phenylene di-amine.

white oils, having Saybolt viscosities at F. ranging from 75 to seconds, are generally used. Petrolatums may also he used. Waxes having higher and lower melting points than those given above as well as refined oils having higher and lower viscosities than those given above may also be used. My invention is not limited, however, to waxes, petrolatums and oils having the above physical properties.

Examples of the antioxidants which may be employed in my process are the classes of alkyl phenols, poly-hydroxy benzene compounds, naphthols, aromatic amines and aminophenols. Examples of the alkyl phenols are tri-butyl phenol, tertiary butyl phenol, tertiary alkyl phenols generally and ootyl phenol. Examples of the poly-hydroxy benzenes and derivatives are hydroquinone, pyrogallol, catechol, alkylated dihydroxy benzene such as 1:2-di-methyl-3z6-dihydroxy benzene, 1 :2-di-methyl-4 5-di-hydroxy benzene, 1 3-di-ethyl-2 5-di-hydroxy benzene, tertiary butyl catechol, ethyl pyrogallol, alkoxy hydroxy benzenes such as methoxy hydroquinone, pyrogallol-l-methyl ether, ethoxy catechol and the like. Examples of the naphthols are alpha naphthol, beta naphthol,'1:2-di-hydroxy naphthalene and 1:4-di-hydroxy naphthalene. Examples of the aromatic amines are alpha naphthylamine, phenyl alpha naphthylamine, alkyl alpha naphthylamines such as the methyl and ethyl derivatives, poly amines such as para Examples of the aminophenols are ortho-aminophenol, para-aminophenol, alkyl substituted aminophenols such as dimethyl para-aminophenol, di-butyl aminophenol, and di-ethyl aminocresol, aryl aminophenols such as phenyl-aminophenol, and aralkyl aminophenols such as benzyl aminophenol and the like. ,7

The foregoing specification and examples will serve to define the scope of my invention and make its advantages apparent to those skilled in the art to Which it pertains. The specific antioxidants mentioned are given for illustrative purposes and are not intended to restrict the scope of the invention. It will be evident that the invention is not limited to the specific hydrocarbon coating materials herein described.

This application is a division of Serial No. 116,233, filed December 16, 1936.

I claim:

1. A process of making a flexible sheet packaging material comprising first applying to the sheet oxidant which is spread over the entire surface.

thereof and then applying a non-antioxygenic water repellent coating material, said antioxidant being an alkyl alpha naphthylamine.

3. A process of making a flexible sheet packaging material comprising first applying to the sheet packaging material a surfacing of w an antioxidant which is spread over the entire surface thereof and then applying a non-antioxygenic water repellent coating material, said antioxidant being alpha naphthylamine. v I

4. A process of making a flexible sheet packaging material comprising first applying to the sheet packaging material a surfacing of an antioxidant which is spread over the entire surface thereof and then app yin a -an xy ni water repellent coating material, said antioxidant being phenyl alpha naphthylamine.

5. The method of preparing a hydrocarbo coated paper which is stable against oxidation, which comprises impregnating the paper surface with a small amount of an aromatic amine and then coating the thus treated paper with a hydrocarbon coating material selected from the group consisting of paraflin wax, petrolatum and refined hydrocarbon oils.

6. A process of making a paper packaging material comprising first applying to the paper pack: aging material a surfacing of an antioxidant which is spread over the'entire surface thereof and then applying a non-antioxygenic water repellent coating material, said antioxidant being an aromatic amine and said water repellent coating material being paraflin.

CLARENCE M. LOANE. 

